GoldFish are doing well - active, hungry and finish whatever little I put in within 2 minutes.

Additional comment - water seems clear - starting to see brown lining around the edge of the grow bed.

Nothing seems to grow - some seedlins sprouted but seems to be not growing. Put a couple of small flowering plants after washing with rain water a week ago. Seems to be withering.

I know it's driving me nuts not to see any growth. But I know patience and time needed. How long should I wait before changing anything. I don't want to make too many changes (learnt this from tuning PID controllers) for slow responding systems.

With your ammonia that high you are probably still at the start of your cycle. Normal pattern is that the ammonia goes up first then goes down as the nitrites start getting higher. If you have a heavy loaded tank the ammonia will stay high much longer & extend the cycling process. I started a fishless cycle on a 30 gallon tank over a month ago & even with regular seeding of nitrifying bacteria it's finally getting to the point that I'm willing to add in the fish. I've had freshwater aquariums all my life & remember one taking over 6 months to finish cycling but that was when I got impatient & stocked it too heavily, too fast.

I read a paper awhile ago that concluded that high nitrites inhibited growth in tomatoes & there are a number of agriculture studies on its toxic effects on forage especially if there is a deficiency of iron & magnesium in the soil. This may have something to do with your plants not growing well.

I'm much more familiar with the aquaculture side of aquaponics. I would be doing daily water changes with concentrations like you have in your tank. I don't think that the plants will be killed by the ammonia & nitrites but your fish eventually will if you don't take steps to reduce the toxins in the water.

Bright Agrotech has some really great videos on water quality, you should check out their website.

When I started with AP I found that I planted my seedlings to shallow - as there is ~ 1-2" media above high water mark to inhibit algae growth. Now I plant them deep (stem/root) at high water mark and the seedlings usually respond within a day.

In place of NITROSOL you can also use SEAGROW or similar multi-nutrient - again just check that it's fish friendly - most of the nutrients plants require will be in there and will help to kick start the system.

Just check your pH against plant preference - should be some graphs on this site.

Your plants will do much better at a lower pH. 8.0 is great for nitrifying bacteria, but not an optimal range for plant health. At the very least, bring it down to 6.8-7.0.

Also, your KH is pretty high (assuming it's 10 dKH and not 10ppm), so it may take a little extra acid to get your pH down. Take your time, track the effect the acid you add is having on your water's pH and KH, and try not to move your pH more than .2 per day.